Odor removal and stabilization of phosphate-containing pesticides

A deodorized and stabilized pesticidal composition comprises a dithiophosphate of the formula: in which R1 and R2 are aliphatic or aromatic hydrocarbon radicals, and R3 and R4 are hydrogen, or aliphatic or aromatic hydrocarbon radicals with a minor amount of a peroxide, e.g. O,O - dimethyl - S - (1,2 - dicarbethoxyethyl) - dithiophosphate treated with a minor amount, e.g. from about 0.01 to about 1.0 per cent by weight of a peroxide, e.g. 2,2-bis-(tert.-butylperoxy) butane, cumene hydroperoxide, di-tert.-butyl peroxide, pinene hydroperoxide, butyl - pentamethylethyl peroxide, tert.-butyl hydroperoxide, hydrogen peroxide, and benzoyl peroxide. Specification 699,522 is referred to.